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Roof leaks can cause major problems if found too late. It’s all too easy to see when you have a leaky roof – stains on the ceiling are an obvious sign. Sometimes you can also see discolouration on the walls or floors and smell mould.

Discovering the source of leaks however, can be far trickier. Water can travel quite lengthy distances before finding an entry point in one place, dripping down in another and eventually soaking into the ceiling.

The areas that are often the sources of leaks are:

• Roof cladding – Roof cladding is used in order to give your roof a weatherproof layer and to stop water and to and other elements entering your home.
• Roof Flashing – Roof flashing is installed at any break in a shingled roofline to prevent leaks.This is most often the culprit of roof leaks. Roof flashings come in a wide variety of shapes, sizes and functions with different designs and materials dedicated to each type of roofing intersection. Plumbing vent flashings are the most common source of leaks. Cracked rubber around the plumbing pipe is often a tell-tale sign of a leak. Repairs or poor craftsmanship in wall step and furnace flashings can also leave openings unprotected from the elements.
• Roof shingles – These are a roof covering consisting of individual overlapping elements. These elements are normally flat rectangular shapes that are laid in rows without the side edges overlapping; a single layer is used to ensure a water-resistant result.
• Insulation – This is the material (usually fibreglass sheets, reflective foil, boards or pink batts) that has been laid to reduce heat flow into and out of your home as appropriate to the season.

You should also check any areas near vents, pipes, gutters and fans as well as any ‘valleys’ – valleys are areas where two planes of the roof meet. As the shingle for the valley has to be trimmed to fit, if this hasn’t been done correctly, water can travel along the top of the shingle and find its way inside your house. If you have a house with a chimney, make sure you take a good look around as chimneys have four different types of flashing, any of which could be a source of potential leaks.

How to detect leaks

1. You may like to stand outside your house with a pair of binoculars and thoroughly examine whether there are any irregularities on your roof such as cracks, tears, rot or missing pieces of the roof covering materials.
2. The best way to detect leaks is to follow a roofer’s advice and ‘think like water’, meaning you should always aim to discover a leak and then try to trace it back to its source.
3. If you examine the roof from underneath, in the roofspace on a very rainy day, you should be able to retrace the water’s flow.
4. If you have an attic, take the time to investigate it properly. Look for any discolouration of wood and signs of mould. The shape of a ceiling stain may also give you clues about where exactly the problem may be. For instance, if the stain is in a line, there could be problem in the rafters which is allowing a trickle of water. If it’s a single stain, the source may be a small hole in the roof directly above the stain.
5. Take your flashlight into the attic on a rainy day and once you locate the source of the water, mark the area (you could use a nail for this). On a nice day, have a helper tap on the mark while you’re on the roof. Doing this will help you to pinpoint the location on the exterior of the roof so you can know where to lay new shingles or roofing cover.
6. If it isn't raining, you can sometimes locate the origin of a roof leak by examining the roof framing timbers. White powdery trails of mineral salt deposits can sometimes be left behind after water evaporates from the timbers. Brown stains on timber can also be a guide, though sometimes these stains have nothing to do with the roof leaking.
7. You can also bring a garden hose up on the roof if it isn’t raining to test for leaks. Run a small amount of water over where you think the leak is or if you’re not sure yet, make sure you are systematic and water in sections. Work slowly as you need to let the water run long enough to test the area and it takes some time for water to begin dripping inside. Adjust the hose every now and then so that water flows across dry portions of the roof. While you do all this, you should have a helper positioned in the attic with a flashlight looking for moisture and marking the location of any leaks.
8. Holes or rust decay in metal roofs will show up brightly if you are in the roofspace during the day.
9. If you have a flat roof rather than a sloped one, unfortnately your roof is more susceptible to leakage. The source of a leak with a sloped roof is easier because the water runs off the slope in one direction whereas with a flat roof, water can travel in any direction. You may need to call in a professional who can use special infrared technology to locate the leak.

Once you’ve detected the source of the leak, the next step is to repair the leak. It’s also important to maintain your roof and gutters regularly - don’t wait until water is dripping on your head to address problems because then replacing the roof becomes cheaper than fixing it.